The prior art includes a "window shade" deployed space-fed phased array radar antenna which is particularly suited for use in space. The rolled antenna is advantageous because it minimizes storage space aboard a spacecraft. When the spacecraft achieves selected orbit, the antenna is deployed and the "window shade" structure becomes unrolled to a fully expanded operative condition. Such an antenna consists of a low-power RF feed which illuminates a lens aperture membrane. Active transmit/receive (T/R) modules in the aperture membrane receive radar pulses from the ground, amplify them, and perform beam-steering phase shifts so that the signal may be re-transmitted toward a target of interest in space. The reflected energy is received in reverse order, being amplified by the T/R modules then focused back onto the space feed. Radar processors and supporting subsystems are located in a bus at the base of a feed mast. A tensioned three-layer membrane constitutes the aperture and provides a very lightweight, yet sufficiently flat, aperture plane. Array flatness requirements for the space-fed approach are less severe than for corporate-fed approaches by an order of magnitude. The membrane aperture can be rolled up onto a drum resulting in a simple, compact, and repeatable method for deployment/retraction of the antenna.
When the antenna is deployed, it is necessary to space the antenna planes from a common ground plane. This cannot be done with simple spacers because in the stowed condition the planes are compacted against one another in order to save space. Thus, it is necessary to have some sort of hinged spacer which extends the planes in parallel spaced relationship to one another when deployed. In the prior art each antenna plane is held in place by two Vespel springs which are attached to adjacent antenna planes using hinge pins. In addition, one hinge bar is pinned to the ground plane and antenna planes on either side to maintain separation between the three membrane layers. Each hinge bar installation currently requires three pins plus a doubler (base) on the ground plane. The installation of the current hinge pins requires time-consuming hand assembly.